diff --git a/.changeset/fix-next-build-stale-socket.md b/.changeset/fix-next-build-stale-socket.md
new file mode 100644
index 0000000000..c3fd808f2d
--- /dev/null
+++ b/.changeset/fix-next-build-stale-socket.md
@@ -0,0 +1,7 @@
+---
+"@workflow/next": patch
+---
+
+fix(next): guard socket-info filesystem fallback behind lazy discovery flag
+
+Prevents `ECONNREFUSED` during `next build` when a stale `workflow-socket.json` file exists from a previous `next dev` session.
diff --git a/.changeset/fix-step-bundle-dynamic-imports.md b/.changeset/fix-step-bundle-dynamic-imports.md
new file mode 100644
index 0000000000..d080230c46
--- /dev/null
+++ b/.changeset/fix-step-bundle-dynamic-imports.md
@@ -0,0 +1,7 @@
+---
+"@workflow/builders": patch
+---
+
+fix(builders): add `webpackIgnore` comments to dynamic imports in generated step bundle
+
+Prevents Turbopack/webpack "Module not found" errors for runtime-resolved dynamic `import()` calls (e.g. from `@vercel/queue`) that are inlined into the step route bundle.
diff --git a/packages/builders/src/base-builder.ts b/packages/builders/src/base-builder.ts
index 25762fa47a..9b2e290768 100644
--- a/packages/builders/src/base-builder.ts
+++ b/packages/builders/src/base-builder.ts
@@ -589,6 +589,22 @@ export abstract class BaseBuilder {
 
     const stepsResult = await esbuildCtx.rebuild();
 
+    // Post-process the generated step bundle to add bundler-ignore comments
+    // to dynamic `import()` calls with non-literal arguments (e.g. variables,
+    // expressions).  These dynamic imports are resolved at runtime and should
+    // not be traced by downstream bundlers like Turbopack/webpack, which would
+    // otherwise emit "Module not found" errors for unresolvable paths.
+    if (outfile) {
+      const bundleContent = await readFile(outfile, 'utf8');
+      const processed = bundleContent.replace(
+        /\bimport\((?!\s*["'`])/g,
+        'import(/* webpackIgnore: true */ '
+      );
+      if (processed !== bundleContent) {
+        await writeFile(outfile, processed);
+      }
+    }
+
     this.logEsbuildMessages(stepsResult, 'steps bundle creation');
     this.logBaseBuilderInfo(
       'Created steps bundle',
diff --git a/packages/next/src/loader.ts b/packages/next/src/loader.ts
index e04a2b219e..dde704b2e7 100644
--- a/packages/next/src/loader.ts
+++ b/packages/next/src/loader.ts
@@ -178,6 +178,14 @@ function getSocketInfoFilePath(): string | null {
     return configuredPath;
   }
 
+  // Only fall back to filesystem discovery when deferred (lazy) discovery is
+  // active.  Without this guard, a stale socket-info file left behind by a
+  // previous `next dev` session causes ECONNREFUSED during eager builds
+  // (i.e. `next build` without `lazyDiscovery`).
+  if (process.env.WORKFLOW_NEXT_LAZY_DISCOVERY !== '1') {
+    return null;
+  }
+
   // Fallback for worker processes that don't inherit dynamic env updates
   // from the process that created the socket server.
   const distDir = process.env.WORKFLOW_NEXT_DIST_DIR || '.next';